Apparatus and methods for selectively etching silicon oxide films

ABSTRACT

An apparatus and methods for selectively etching a particular layer are disclosed. The apparatus and methods are directed towards maintaining the etch rate of the particular layer, while keeping intact a non-etched layer. A gas mixture may be flowed onto the substrate in separate loops having an oxide layer and an oxynitride layer as an etch layer and a nitride layer as a non-etched layer, for example. A reaction between the resulting gas mixture and the particular layer takes place, resulting in etching of the oxide layer and the oxynitride layer while maintaining the nitride layer in the above example.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Non-provisional of, and claims priority to and thebenefit of, U.S. Provisional Patent Application No. 63/007,276, filedApr. 8, 2020 and entitled “APPARATUS AND METHODS FOR SELECTIVELY ETCHINGSILICON OXIDE FILMS,” which is hereby incorporated by reference herein.

FIELD OF INVENTION

The present disclosure generally relates to an apparatus for processingsemiconductor wafers. More particularly, the disclosure relates to anapparatus and methods for selectively etching a particular film (such assilicon oxide) on a semiconductor wafer while keeping another filmintact.

BACKGROUND OF THE DISCLOSURE

During formation of semiconductor devices, there is a significantlikelihood that multiple films would be formed. For example, there maybe both silicon nitride films and silicon oxide films deposited on apatterned wafer.

Certain applications may require that the processed patterned wafer havea particular film on it, such as silicon nitride, while removing anotherfilm. These may include logic and memory applications. In these cases,failing to remove one film, such as silicon oxide, may result inmalfunctioning of the devices. In addition, processes to remove asilicon oxide film may result in thinning, damage, or removal of thesilicon nitride film, reducing the ability of the device to storecharges, which may prove to be critical for performance in memoryapplications for example.

As a result, an apparatus and methods that exhibit selectivity foretching one particular film over another are desired.

SUMMARY OF THE DISCLOSURE

In accordance with at least one embodiment of the invention, a methodfor selectively etching a film (e.g., a film used in the formation ofsemiconductor devices) deposited on a substrate is disclosed. The methodcomprises: providing a substrate in a reaction chamber of asemiconductor processing device, wherein the substrate has an oxidelayer, a nitride layer, and an oxynitride layer; performing a firstetching process, wherein the first etching process comprises flowing ahydrogen precursor gas, a fluorine precursor gas, and an inert gas ontothe substrate; performing a second etching process, wherein the secondetching process comprises flowing a hydrogen precursor gas, a fluorineprecursor gas, and an inert gas onto the substrate; wherein the firstetching process is repeated a predetermined number of times and thefirst etching process removes the oxynitride layer from the substrateand keeps the nitride layer substantially intact; and wherein the secondetching process is repeated a predetermined number of times and thesecond etching process removes the oxide layer from the substrate andkeeps the nitride layer substantially intact.

In accordance with at least one embodiment of the invention, a systemfor selectively etching a film disposed on a substrate is disclosed. Thesystem comprises: a reaction chamber configured to hold and process asubstrate, wherein the substrate has an oxide layer, a nitride layer,and an oxynitride layer; a fluorine precursor source configured toprovide a fluorine precursor gas, the fluorine precursor gas comprisingat least one of: nitrogen trifluoride (NF₃); carbon tetrafluoride (CF₄);sulfur hexafluoride (SF₆); hydrogen fluoride (HF); hydrofluoric acid(HF) with water vapor; or fluorine (F₂); a hydrogen precursor sourceconfigured to provide a hydrogen precursor gas, the hydrogen precursorgas comprising at least one of: ammonia (NH₃); hydrazine (N₂H₄); urea(NH₂CONH₂); or hydrogen (H₂); and an inert gas source configured toprovide an inert gas, wherein the inert gas comprises at least one of:argon; krypton; helium; xenon; or nitrogen; wherein a gaseous mixture ofthe fluorine precursor gas, the hydrogen precursor gas, and the inertgas is flowed onto the substrate, resulting in an etching of the oxidelayer and the oxynitride layer while maintaining intact the nitridelayer in an etching process.

This summary is provided to introduce a selection of concepts in asimplified form. These concepts are described in further detail in thedetailed description of example embodiments of the disclosure below.This summary is not intended to identify key features or essentialfeatures of the claimed subject matter, nor is it intended to be used tolimit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

These and other features, aspects, and advantages of the inventiondisclosed herein are described below with reference to the drawings ofcertain embodiments, which are intended to illustrate and not to limitthe invention.

FIGS. 1A-1D are cross-sectional illustrations of a semiconductor devicein accordance with at least one embodiment of the invention.

FIG. 2 is a flowchart of a method for selectively etching a film inaccordance with at least one embodiment of the invention.

FIG. 3 is a schematic illustration of a semiconductor processing systemin accordance with at least one embodiment of the invention.

FIG. 4 is a schematic illustration of a semiconductor processing systemin accordance with at least one embodiment of the invention.

It will be appreciated that elements in the figures are illustrated forsimplicity and clarity and have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexaggerated relative to other elements to help improve understanding ofillustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below.

The illustrations presented herein are not meant to be actual views ofany particular material, structure, or device, but are merely idealizedrepresentations that are used to describe embodiments of the disclosure.

Various embodiments are related to a cleaning process for removing asilicon oxide, a germanium oxide, or a metal oxide material from anexposed surface of a substrate. The embodiments may also be used toremove at least one of: silicon; metals in its elemental form; alloys ofvarious metals; oxides related to the alloys of various metals; silicon;or germanium. It may be understood that a resulting cleaned surface willallow for formation of high quality semiconductor layers, such asepitaxially grown silicon, for example.

FIG. 1A illustrates a semiconductor device 100 prior to undergoing acleaning process. The semiconductor device 100 comprises a substrate110; an intermediate layer 120; a nitride layer 130; and an oxide layer140. The substrate 110 may comprise at least one of: silicon or silicongermanium. The intermediate layer 120 may comprise a dielectric layer,such as silicon nitride, silicon carbonitride, or silicon boronitride,for example. The intermediate layer 120 may comprise other materials aswell, such as silicon carbide or silicon oxycarbide, for example. Thenitride layer 130 may comprise silicon nitride or a metal nitride, suchas aluminum nitride. The oxide layer 140 may comprise at least one of:silicon oxide; germanium oxide; aluminum oxide; cobalt oxide; ortungsten oxide, for example.

Formation of the layers may take place via epitaxial deposition,chemical vapor deposition (CVD), atomic layer deposition (ALD), plasmaenhanced atomic layer deposition (PEALD), or plasma enhanced chemicalvapor deposition (PECVD), for example. It is desired that a cleaningprocess be able to entirely remove or remove a targeted thickness of theoxide layer 140, but keep the nitride layer 130, the intermediate layer120, and the substrate 110 intact. Such a result is shown in FIG. 1D.

FIG. 1B illustrates the semiconductor device 100 after a period of timewithin a reaction chamber. The period of time may be between an initialdeposition of the nitride layer 130 and an etching step of the oxidelayer 140. This period of time may be unavoidable due to thecomplexities involved with manufacturing integrated circuits. Duringthat period of time, the semiconductor device 100 is exposed to theambient environment of the reaction chamber.

Exposure of the semiconductor device 100 to the ambient environmentcauses oxidation of the nitride layer 130, resulting in the formation ofan oxynitride layer 150. The longer the oxidation occurs, the thickerthe oxynitride layer 150 may become. The oxynitride layer 150 causes agreater loss of the nitride layer 130, in comparison to a nitride layerthat remains unoxidized.

Protection of the nitride layer 130 is desirable as the nitride layer130 may be a crucial part of an integrated circuit, or it may be a masklayer to protect another layer on the patterned substrate. Presence ofthe oxynitride layer 150 may prove to be problematic as removal of theoxynitride layer 150 is a self-catalyzed reaction facilitated by thebyproduct water (H₂O) molecules formed on the surface of the substrate.The existence of these water molecules may lead to undesired etching ofthe nitride layer 130 if the etching is not stopped after the oxynitridelayer 150 is removed. As a result, the etching step of the oxynitridelayer 150 may be stopped and a bake step may be employed to remove thebyproduct water (H₂O) molecules in order to preserve the nitride layer130.

FIG. 1C illustrates the semiconductor device 100 after a first etchprocess loop takes place. The first etch process loop ideally removes anentire portion of the oxynitride layer 150 and a portion of the oxidelayer 140. It may turn out that a portion of the nitride layer 130 isalso removed, but it is desired that removal of the nitride layer 130 islimited.

FIG. 1D illustrates the semiconductor device 100 after a second etchprocess loop takes place. The second etch process loop ideally removesthe remainder of the oxide layer 140. Again, it may also turn out that aportion of the nitride layer 130 is removed, but is desired that removalof the nitride layer 130 is limited.

FIG. 2 illustrates an etching process 200 that may comprise: (1) a stepfor providing a substrate in a reaction chamber 210; (2) a step for afirst etch process 220; (3) a step for an optional mild bake 230; (4) astep for a second etch process 250; (5) a step for an optional mild bake260; and (6) a step for performing additional processing on thesubstrate 280.

The first etch process 220 and the optional mild bake 230 may be doneagain through a first etch process repeat step 240. The first etchprocess 220, the optional mild bake 230, and the first etch processrepeat step 240 together comprise a first etch process loop. The firstetch process repeat step 240 may be done more than once. Similarly, thesecond etch process 250 and the optional mild bake 260 may be done againthrough a second etch process repeat step 270. The second etch process250, the optional mild bake 260, and the second etch process repeat step270 together comprise a second etch process loop. The second etchprocess repeat step 270 may also be done more than once.

The step 210 may be done in a reaction chamber for performing epitaxialdeposition, chemical vapor deposition (CVD), atomic layer deposition(ALD), plasma enhanced atomic layer deposition (PEALD), or plasmaenhanced chemical vapor deposition (PECVD). The step 210 may also takeplace in a vertical furnace. A deposition step may take place after thesubstrate arrives into the reaction chamber and before the first etchprocess 220, resulting in a film deposited on the substrate. Forexample, the deposition step may result in the formation of the nitridelayer 130 or the oxide layer 140 on the substrate.

Directed to removing the oxide layer 140 and the oxynitride layer 150,the first etch process 220 may comprise flowing a combination of gasesinto the reaction chamber. The combination of gases may include afluorine gas, a hydrogen gas, and an inert gas. The combination of gasesmay include activated or radical versions of the gases listed above. Thefluorine gas may comprise at least one of: nitrogen trifluoride (NF₃);carbon tetrafluoride (CF₄); sulfur hexafluoride (SF₆); hydrogen fluoride(HF); hydrofluoric acid (HF) with water vapor; or fluorine (F₂). Theinert gas may comprise at least one of: argon (Ar); krypton (Kr); helium(He); xenon (Xe); or nitrogen (N₂). The hydrogen gas may comprise atleast one of: ammonia (NH₃); hydrazine (N₂H₄); urea (NH₂CONH₂); hydrogen(H₂); an alcohol, such as methanol, ethanol, propanol, or isopropanol;an acidic gas, such as formic acid (HCOOH), acetic acid (CH₃COOH), or anacidic anhydride; or a mixture of the above.

In one embodiment of the invention, the fluorine gas and the inert gasmay be activated by a remote plasma unit (RPU) prior to being combinedwith the hydrogen gas. In another embodiment of the invention, thefluorine gas, the inert gas, and the hydrogen gas may be combined in agas manifold prior to being flowed into the reaction chamber.

The first etch process 220 may have settings that facilitate removal ofthe oxynitride layer 150. For example, the reaction chamber may be setto a temperature ranging between −20° C. and 150° C., between 0° C. and100° C., or between 5° C. and 65° C. The duration of the first etchprocess 220 may be between 1 and 30 seconds, between 3 and 20 seconds,or between 3 and 10 seconds. The pressure of the reaction chamber duringthe first etch process 220 may be between 0.1 and 600 Torr, between 0.5and 50 Torr, or between 0.5 and 4 Torr.

The mild bake step (optional) 230 may be employed after the first etchprocess 220. The first etch process 220 may result in formation ofreaction byproducts that require removal. For example, during the firstetch process 220, water (H₂O) molecules may be formed on the surface ofthe substrate. The mild bake step 230 would remove the H₂O moleculesthat could potentially interfere with subsequent processing steps.

During the mild bake step 230, a flow of inert gas into the reactionchamber may take place. The inert gas may comprise at least one of:argon (Ar); krypton (Kr); helium (He); xenon (Xe); or nitrogen (N₂). Inaddition, the reaction chamber may be set to a temperature rangingbetween 50° C. and 400° C., between 75° C. and 300° C., or between 90°C. and 250° C. The duration of the mild bake step 230 may be between 5and 120 seconds, between 10 and 60 seconds, or between 10 and 30seconds.

Directed to removing the oxide layer 140 and keeping the nitride layer130 intact, the second etch process 250 may comprise flowing acombination of gases into the reaction chamber. The combination of gasesmay include a fluorine gas, a hydrogen gas, and an inert gas. Thecombination of gases may include activated or radical versions of thegases listed above. The fluorine gas may comprise at least one of:nitrogen trifluoride (NF₃); carbon tetrafluoride (CF₄); sulfurhexafluoride (SF₆); hydrogen fluoride (HF); hydrofluoric acid (HF) withwater vapor; or fluorine (F₂). The inert gas may comprise at least oneof: argon (Ar); krypton (Kr); helium (He); xenon (Xe); or nitrogen (N₂).The hydrogen gas may comprise at least one of: ammonia (NH₃); hydrazine(N₂H₄); urea (NH₂CONH₂); hydrogen (H₂); an alcohol, such as methanol,ethanol, propanol, or isopropanol; an acidic gas, such as formic acid(HCOOH), acetic acid (CH₃COOH), or an acidic anhydride; or a mixture ofthe above.

In one embodiment of the invention, the fluorine gas and the inert gasmay be activated by a remote plasma unit (RPU) prior to being combinedwith the hydrogen gas. In another embodiment of the invention, thefluorine gas, the inert gas, and the hydrogen gas may be combined in agas manifold prior to being flowed into the reaction chamber.

The second etch process 250 may have settings that facilitate removal ofthe oxide layer 140. For example, the reaction chamber may be set to atemperature ranging between −20° C. and 150° C., between 0° C. and 100°C., or between 5° C. and 65° C. The duration of the second etch process250 may be between 5 and 120 seconds, between 5 and 60 seconds, orbetween 5 and 30 seconds. The duration of the second etch process 250may be longer than that of the first etch process 220 in order to resultin a greater etch rate of the desired film (in this case, the oxide film140). The pressure of the reaction chamber during the second etchprocess 250 may be between 0.1 and 600 Torr, between 0.5 and 50 Torr, orbetween 0.5 and 4 Torr.

The mild bake step (optional) 260 may be employed after the second etchprocess 250. The second etch process 250 may result in formation ofreaction byproducts that require removal. It is not expected during thesecond etch process 250 that water (H₂O) molecules may be formed on thesurface of the substrate; however, other byproducts may be formed, suchas non-catalyzing reaction byproducts. The mild bake step 260 wouldremove these byproducts (as well as any water molecules that may exist)that could potentially interfere with subsequent processing steps.

During the mild bake step 260, a flow of inert gas into the reactionchamber may take place. The inert gas may comprise at least one of:argon (Ar); krypton (Kr); helium (He); xenon (Xe); or nitrogen (N₂). Inaddition, the reaction chamber may be set to a temperature rangingbetween 50° C. and 400° C., between 75° C. and 300° C., or between 90°C. and 250° C. The duration of the mild bake step 260 may be between 5and 120 seconds, between 10 and 60 seconds, or between 10 and 30seconds.

The first etch process repeat step 240 may be repeated a differentnumber of times in comparison to the second etch process repeat step270. Such may be as a result of a different thickness of the oxynitridelayer 150 and the oxide layer 140 needing to be removed from thesubstrate. By separating the first etch process repeat step 240 from thesecond etch process repeat step 270, a greater selectivity of etchingthe oxide layer 140 over the nitride layer 130 may be achieved. Forexample, an etching process in accordance with at least one embodimentof the invention may achieve an etching ratio (etching oxidelayer:etching nitride layer) greater than 8:1, greater than 16:1, orgreater than 40:1.

In accordance with another embodiment of the invention, selectivity ofthe etching process may be defined in a way that minimizes removal ofthe nitride layer 130 when a certain thickness of the oxide layer 140 isrequired to be removed by a specific application. The etching process inaccordance with this invention may reduce an amount of loss in thenitride layer 130 with respect to the entire oxynitride layer 150 andthe nitride layer by a percentage greater than 20%, greater than 50%, orgreater than 80%.

After the second etch process repeat step 270 is complete, the substratemay undergo other processing in a step for performing additionalprocessing 280. The additional processing step 280 may comprisedeposition processes such as epitaxial deposition, chemical vapordeposition (CVD), atomic layer deposition (ALD), plasma enhanced atomiclayer deposition (PEALD), or plasma enhanced chemical vapor deposition(PECVD), for example. Alternatively, the additional processing step 280may comprise different etch processes to potentially remove a differentmaterial; for example, the different etch process may be used to removea carbon-containing layer.

In accordance with at least one embodiment of the invention, a substrateprocessing system 300 is disclosed in FIG. 3. The substrate processingsystem 300 comprises: a reaction chamber 310; a remote plasma unit 320;a fluorine precursor source 330A; an inert gas source 330B; a hydrogenprecursor source 330C; a pathway 340 disposed between the remote plasmaunit 320 and the reaction chamber 310; and a plurality of gas lines350A-350C linking the gas sources 330A-330C with the remote plasma unit320 and the pathway 340.

The reaction chamber 310 comprises a substrate holder 310A configured tohold a substrate to be processed; and a showerhead 310B for distributingthe gas onto the substrate. The substrate holder 310A may have anability to control its temperature among different parts of thesubstrate holder 310A. The fluorine precursor source 330A and the inertgas source 330B provide gases that are activated by the remote plasmaunit 320. The remote plasma unit 320 may comprise one created by MKSInstruments, Inc. or by Advanced Energy Industries, Inc.

In accordance with at least one embodiment of the invention, a substrateprocessing system 400 is disclosed in FIG. 4. The substrate processingsystem 400 comprises: a reaction chamber 410; a gas manifold 420; afluorine precursor source 430A; a hydrogen precursor source 430B; aninert gas source 430C; a pathway 440 disposed between the gas manifold420 and the reaction chamber 410; and a plurality of gas lines 450A-450Clinking the gas sources 430A-430C with the gas manifold 420.

The reaction chamber 410 comprises a substrate holder 410A configured tohold a substrate to be processed; and a showerhead 410B for distributingthe gas onto the substrate. The gas manifold 420 receives the gases fromthe different sources 430A-430C and mixes them prior to the gasesentering the reaction chamber 410. The substrate holder 410A may have anability to control its temperature among different parts of thesubstrate holder 410A.

In an exemplary process in accordance with at least one embodiment ofthe invention, a substrate may have both a silicon oxide film and asilicon nitride film deposited on it. The silicon nitride film may be acritical part of the integrated circuit or a mask layer to protectanother layer on the patterned substrate. During processing steps, a topportion of the silicon nitride layer may be exposed to an ambientenvironment, converting a portion of the silicon nitride layer into asilicon oxynitride layer. Processes in accordance with at least oneembodiment of the invention may be used to remove both the silicon oxidelayer and the silicon oxynitride layer, but keep the silicon nitridelayer intact.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the aspects and implementations in any way. Indeed, for thesake of brevity, conventional manufacturing, connection, preparation,and other functional aspects of the system may not be described indetail. Furthermore, the connecting lines shown in the various figuresare intended to represent exemplary functional relationships and/orphysical couplings between the various elements. Many alternative oradditional functional relationship or physical connections may bepresent in the practical system, and/or may be absent in someembodiments.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. Thus, the various acts illustrated may beperformed in the sequence illustrated, in other sequences, or omitted insome cases.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems, and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

1. A method for selectively etching a film disposed on a substrate, themethod comprising: providing a substrate in a reaction chamber of asemiconductor processing device, wherein the substrate has an oxidelayer, a nitride layer, and an oxynitride layer; performing a firstetching process, wherein the first etching process comprises flowing ahydrogen precursor gas, a fluorine precursor gas, and an inert gas ontothe substrate; performing a second etching process, wherein the secondetching process comprises flowing a hydrogen precursor gas, a fluorineprecursor gas, and an inert gas onto the substrate; wherein the firstetching process is repeated a predetermined number of times and thefirst etching process removes the oxynitride layer from the substrateand keeps the nitride layer substantially intact; and wherein the secondetching process is repeated a predetermined number of times and thesecond etching process removes the oxide layer from the substrate andkeeps the nitride layer substantially intact.
 2. The method of claim 1,wherein the first etching process further comprises performing a mildbake step on the substrate.
 3. The method of claim 1, wherein the secondetching process further comprises performing a mild bake step on thesubstrate.
 4. The method of claim 1, wherein the hydrogen precursor gascomprises at least one of: ammonia (NH₃); hydrazine (N₂H₄); or urea(NH₂CONH₂).
 5. The method of claim 1, wherein the fluorine precursor gascomprises at least one of: nitrogen trifluoride (NF₃); carbontetrafluoride (CF₄); sulfur hexafluoride (SF₆); hydrogen fluoride (HF);hydrofluoric acid (HF) with water vapor; or fluorine (F₂).
 6. The methodof claim 1, wherein the hydrogen precursor gas comprises at least oneof: hydrogen (H₂); hydrogen fluoride (HF); hydrogen chloride (HCl);water (H₂O); an alcohol, such as methanol, ethanol, propanol, orisopropanol; an acidic gas, such as formic acid (HCOOH), acetic acid(CH₃COOH), or an acidic anhydride; or a mixture of any of the above. 7.The method of claim 1, wherein the oxide layer comprises at least oneof: silicon oxide; germanium oxide; aluminum oxide; cobalt oxide;tungsten oxide; silicon; germanium; aluminum; cobalt; tungsten; oralloys of various metals.
 8. The method of claim 1, wherein the nitridelayer comprises at least one of: silicon nitride; metal nitride; oraluminum nitride.
 9. The method of claim 1, wherein the inert gascomprises at least one of: argon; krypton; helium; xenon; or nitrogen.10. The method of claim 1, wherein the first etching process has aduration ranging between 1 and 30 seconds, between 3 and 20 seconds, orbetween 3 and 10 seconds.
 11. The method of claim 1, wherein the firstetching process has a temperature ranging between −20° C. and 150° C.,between 0° C. and 100° C., or between 5° C. and 65° C.
 12. The method ofclaim 1, wherein the first etching process has a pressure rangingbetween 0.1 and 600 Torr, between 0.5 and 50 Torr, or between 0.5 and 4Torr.
 13. The method of claim 1, wherein the second etching process hasa duration ranging between 5 and 120 seconds, between 5 and 60 seconds,or between 5 and 30 seconds.
 14. The method of claim 1, wherein thesecond etching process has a temperature ranging between −20° C. and150° C., between 0° C. and 100° C., or between 5° C. and 65° C.
 15. Themethod of claim 1, wherein the second etching process has a pressureranging between 0.1 and 600 Torr, between 0.5 and 50 Torr, or between0.5 and 4 Torr.
 16. A system for selectively etching a film disposed ona substrate, the system comprising: a reaction chamber configured tohold and process a substrate, wherein the substrate has an oxide layer,a nitride layer, and an oxynitride layer; a fluorine precursor sourceconfigured to provide a fluorine precursor gas, the fluorine precursorgas comprising at least one of: nitrogen trifluoride (NF₃); carbontetrafluoride (CF₄); sulfur hexafluoride (SF₆); hydrogen fluoride (HF);hydrofluoric acid (HF) with water vapor; or fluorine (F₂); a hydrogenprecursor source configured to provide a hydrogen precursor gas, thehydrogen precursor gas comprising at least one of: ammonia (NH₃);hydrazine (N₂H₄); urea (NH₂CONH₂); hydrogen (H₂); an alcohol, such asmethanol, ethanol, propanol, or isopropanol; an acidic gas, such asformic acid (HCOOH), acetic acid (CH₃COOH), or an acidic anhydride; or amixture of any of the above; and an inert gas source configured toprovide an inert gas, wherein the inert gas comprises at least one of:argon; krypton; helium; xenon; or nitrogen; wherein a gaseous mixture ofthe fluorine precursor gas, the hydrogen precursor gas, and the inertgas is flowed onto the substrate, resulting in an etching of the oxidelayer and the oxynitride layer while maintaining intact the nitridelayer in the process of claim
 1. 17. The system of claim 16, furthercomprising: a remote plasma unit configured to provide radicals of thefluorine precursor gas and the inert gas.
 18. The system of claim 16,further comprising: a gas manifold configured to mix the fluorineprecursor gas, the hydrogen precursor gas, and the inert gas.
 19. Thesystem of claim 16, wherein the oxide layer comprises at least one of:silicon oxide; germanium oxide; aluminum oxide; cobalt oxide; tungstenoxide; silicon; germanium; aluminum; cobalt; tungsten; or alloys ofvarious metals.
 20. The system of claim 16, wherein the nitride layercomprises at least one of: silicon nitride; metal nitride; or aluminumnitride.